I wanted to tell you that thanks to your explanations it was easier for me to look up reference, (thank you again so much) I found 3 or 4 that I thought could go. On which I was undecided.
So I thought to try this reference. I hope it's fine.
I send what I've done now.
I'm so sorry for the photo, I made some bad shots, I tried to darken lines with gimp, next photos I try to send them better (I sent this anyway because it was without shading, I was right at the beginning).
I'd ask you another question, if you think the size is good, I used an A4 sheet, (bristol sheet, album used for skull, hb pencil.)
it's okay to use portion of the sheet you used (ie if the frame is fine), perhaps better to use even more sheet, leave less edges.
thank you for everything, then if it goes well I will go ahead in the drawing and update.